GPS={

	    PI : 3.14159265358979324,
	    x_pi : 3.14159265358979324 * 3000.0 / 180.0,
	    //偏移量
	    delta : function (lng,lat) {
	        // Krasovsky 1940
	        //
	        // a = 6378245.0, 1/f = 298.3
	        // b = a * (1 - f)
	        // ee = (a^2 - b^2) / a^2;
	        var a = 6378245.0; //  a: 卫星椭球坐标投影到平面地图坐标系的投影因子。
	        var ee = 0.00669342162296594323; //  ee: 椭球的偏心率。
	        var dLat = this.transformLat(lng - 105.0, lat - 35.0);
	        var dLng = this.transformLon(lng - 105.0, lat - 35.0);
	        var radLat = lat / 180.0 * this.PI;
	        var magic = Math.sin(radLat);
	        magic = 1 - ee * magic * magic;
	        var sqrtMagic = Math.sqrt(magic);
	        dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * this.PI);
	        dLng = (dLng * 180.0) / (a / sqrtMagic * Math.cos(radLat) * this.PI);
	        return {'lat': dLat, 'lng': dLng};
	    },
	     
	    //WGS-84 to GCJ-02 大地坐标系转火星坐标系
	    gps_gaode : function (wgsLng,wgsLat) {
	        if (this.outOfChina(wgsLng,wgsLat))
	            return {'lat': wgsLat, 'lng': wgsLng};
	 
	        var d = this.delta(wgsLng,wgsLat);
	        return {'lat' : parseFloat(wgsLat) + parseFloat(d.lat), 'lng' : parseFloat(wgsLng) + parseFloat(d.lng) };
	    },
	    //GCJ-02 to WGS-84 火星坐标系转大地坐标系
	    gaode_gps : function (gcjLng,gcjLat) {
	        if (this.outOfChina(gcjLng,gcjLat))
	            return {'lat': gcjLat, 'lng': gcjLng};
	         
	        var d = this.delta(gcjLng,gcjLat);
	        return {'lat': gcjLat - d.lat, 'lng': gcjLng - d.lng};
	    },
	    //GCJ-02 to WGS-84 exactly
	    gaode_gps_exact : function (gcjLng,gcjLat) {
	        var initDelta = 0.01;
	        var threshold = 0.000000001;
	        var dLat = initDelta, dLng = initDelta;
	        var mLat = gcjLat - dLat, mLng = gcjLng - dLng;
	        var pLat = gcjLat + dLat, pLng = gcjLng + dLng;
	        var wgsLat, wgsLng, i = 0;
	        while (1) {
	            wgsLat = (mLat + pLat) / 2;
	            wgsLng = (mLng + pLng) / 2;
	            var tmp = this.gcj_encrypt(wgsLng,wgsLat)
	            dLat = tmp.lat - gcjLat;
	            dLng = tmp.lng - gcjLng;
	            if ((Math.abs(dLat) < threshold) && (Math.abs(dLng) < threshold))
	                break;
	 
	            if (dLat > 0) pLat = wgsLat; else mLat = wgsLat;
	            if (dLng > 0) pLng = wgsLng; else mLng = wgsLng;
	 
	            if (++i > 10000) break;
	        }
	        //console.log(i);
	        return {'lat': wgsLat, 'lng': wgsLng};
	    },
	    //GCJ-02 to BD-09 火星坐标系转百度坐标系
	    gaode_baidu : function (gcjLng,gcjLat) {
	        var x = gcjLng, y = gcjLat;  
	        var z = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * this.x_pi);  
	        var theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * this.x_pi);  
	        bdLng = z * Math.cos(theta) + 0.0065;  
	        bdLat = z * Math.sin(theta) + 0.006; 
	        return {'lat' : bdLat,'lng' : bdLng};
	    },
		gps_baidu : function(gpsLng,gpsLat){
			var gaode=this.gps_gaode(gpsLng,gpsLat);
			return this.gaode_baidu(gaode.lng,gaode.lat);
		},
	    //BD-09 to GCJ-02
	    baidu_gaode : function (bdLng,bdLat) {
	        var x = bdLng - 0.0065, y = bdLat - 0.006;  
	        var z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * this.x_pi);  
	        var theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * this.x_pi);  
	        var gcjLng = z * Math.cos(theta);  
	        var gcjLat = z * Math.sin(theta);
	        return {'lat' : gcjLat, 'lng' : gcjLng};
	    },
	    //WGS-84 to Web mercator 大地坐标系转墨卡托坐标系
	    //mercatorLat -> y mercatorLon -> x
	    mercator_encrypt : function(wgsLng,wgsLat) {
	        var x = wgsLng * 20037508.34 / 180.;
	        var y = Math.log(Math.tan((90. + wgsLat) * this.PI / 360.)) / (this.PI / 180.);
	        y = y * 20037508.34 / 180.;
	        return {'lat' : y, 'lng' : x};
	        /*
	        if ((Math.abs(wgsLon) > 180 || Math.abs(wgsLat) > 90))
	            return null;
	        var x = 6378137.0 * wgsLon * 0.017453292519943295;
	        var a = wgsLat * 0.017453292519943295;
	        var y = 3189068.5 * Math.log((1.0 + Math.sin(a)) / (1.0 - Math.sin(a)));
	        return {'lat' : y, 'lon' : x};
	        //*/
	    },
	    // Web mercator to WGS-84
	    // mercatorLat -> y mercatorLon -> x
	    mercator_decrypt : function(mercatorLat, mercatorLng) {
	        var x = mercatorLng / 20037508.34 * 180.;
	        var y = mercatorLat / 20037508.34 * 180.;
	        y = 180 / this.PI * (2 * Math.atan(Math.exp(y * this.PI / 180.)) - this.PI / 2);
	        return {'lat' : y, 'lng' : x};
	        /*
	        if (Math.abs(mercatorLon) < 180 && Math.abs(mercatorLat) < 90)
	            return null;
	        if ((Math.abs(mercatorLon) > 20037508.3427892) || (Math.abs(mercatorLat) > 20037508.3427892))
	            return null;
	        var a = mercatorLon / 6378137.0 * 57.295779513082323;
	        var x = a - (Math.floor(((a + 180.0) / 360.0)) * 360.0);
	        var y = (1.5707963267948966 - (2.0 * Math.atan(Math.exp((-1.0 * mercatorLat) / 6378137.0)))) * 57.295779513082323;
	        return {'lat' : y, 'lon' : x};
	        //*/
	    },
	    // two point's distance
	    distance : function (latA, lngA, latB, lngB) {
	        var earthR = 6371000.;
	        var x = Math.cos(latA * this.PI / 180.) * Math.cos(latB * this.PI / 180.) * Math.cos((lngA - lngB) * this.PI / 180);
	        var y = Math.sin(latA * this.PI / 180.) * Math.sin(latB * this.PI / 180.);
	        var s = x + y;
	        if (s > 1) s = 1;
	        if (s < -1) s = -1;
	        var alpha = Math.acos(s);
	        var distance = alpha * earthR;
	        return distance;
	    },
	    //是否在中国
	    outOfChina : function (lng,lat) {
	        if (lng < 72.004 || lng > 137.8347)
	            return true;
	        if (lat < 0.8293 || lat > 55.8271)
	            return true;
	        return false;
	    },
	    transformLat : function (x, y) {
	        var ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));
	        ret += (20.0 * Math.sin(6.0 * x * this.PI) + 20.0 * Math.sin(2.0 * x * this.PI)) * 2.0 / 3.0;
	        ret += (20.0 * Math.sin(y * this.PI) + 40.0 * Math.sin(y / 3.0 * this.PI)) * 2.0 / 3.0;
	        ret += (160.0 * Math.sin(y / 12.0 * this.PI) + 320 * Math.sin(y * this.PI / 30.0)) * 2.0 / 3.0;
	        return ret;
	    },
	    transformLon : function (x, y) {
	        var ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
	        ret += (20.0 * Math.sin(6.0 * x * this.PI) + 20.0 * Math.sin(2.0 * x * this.PI)) * 2.0 / 3.0;
	        ret += (20.0 * Math.sin(x * this.PI) + 40.0 * Math.sin(x / 3.0 * this.PI)) * 2.0 / 3.0;
	        ret += (150.0 * Math.sin(x / 12.0 * this.PI) + 300.0 * Math.sin(x / 30.0 * this.PI)) * 2.0 / 3.0;
	        return ret;
	    }
	
};